Bosnia, Bihać - Željava Air Base - 02.05.2008522 viewsŽeljava Air Base also know as Bihać Air Base was the largest underground airport and military airbase in the former Yugoslavia. http://www.mycity-military.com/Vojno-tehnicka-dostignuca/Enigma-JNA-Podzemni-Aerodrom-Zeljava.htmlcristi